From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DECAEC10F14 for ; Tue, 15 Oct 2019 14:45:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A046C2086A for ; Tue, 15 Oct 2019 14:45:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="O1+hokyY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732712AbfJOOpT (ORCPT ); Tue, 15 Oct 2019 10:45:19 -0400 Received: from mail-vk1-f181.google.com ([209.85.221.181]:36310 "EHLO mail-vk1-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732595AbfJOOpT (ORCPT ); Tue, 15 Oct 2019 10:45:19 -0400 Received: by mail-vk1-f181.google.com with SMTP id w3so4402523vkm.3 for ; Tue, 15 Oct 2019 07:45:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=XROkh959F7qjDHVVNXpDtZJp9FNzqPbbesUV83OOxa4=; b=O1+hokyY3gkds21yf00JwltfESWOHg1hpiqGOLSWHG5168wCiehqZz5qdPAUHzjtJp S7bhiy7sMLAwVf/lWNs916L/ZEnzuXgBROhFG563THi3LYGi42m2TDVAhLJDweA7GOJe PTSj9AYl9N39vBZkifMCSjexn0NfMeWOu1x7rJa4vzN4uzmLMjG7iwe7IY/Abj7DroAV lFftuNQtfer78qyjMJT572ARxAovwue0asW8G/4Vz13VAfm73eTSojE/7NAfIB5ujMSM d91I+p85Gxx1WDyNfOwNuZgsvefS14HWtlpVhBBkZLr3OmatqAEUdQRbMVa9ogT7dIxa jqDQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=XROkh959F7qjDHVVNXpDtZJp9FNzqPbbesUV83OOxa4=; b=U1+g0+pY/wVUryKMGrb4AmUzxu8tdvGgr47xocy0brQE5FEENfGODmlPTFy6t/nEia lG+pjn55cqkX+yY5uAyLFMI0RYr3FBBT1oUiC8O24O0pgaWutGLn3TTud3vcD/C964nm NvLWzE3E8oiF2Bw8/crwDHu7CWXCl9f591STW67wDGm3dTzX2fWGjXnxRnmmk+tapil7 vaVZep4iZkqK2mAMJaOitj2YCIarkLSBF6xYb1+zDhLIoQPqxWpWUxJ858un8cxsn8gU fo2CMroVr5vAdMuV55WXPWZps23rOFGpK7S5Hm+8QmJsNbRQlQAJkFursgPtQho7NkVh y96Q== X-Gm-Message-State: APjAAAXxaQAXEN/WyKuvCJSjgrZH7vQKbVt7cRoJSFej2mtoRFfWHLfJ GHBQpE2mH+IMxrr6IzH2COaP1QcY X-Google-Smtp-Source: APXvYqwxNzPI9+69WXuTEbY6LI/SRGP/UDZE+4vt5l/WobVk4cLmOScuoDXjFuJQ51LJDHI0TZjFJg== X-Received: by 2002:ac5:ccc2:: with SMTP id j2mr19038412vkn.44.1571150717506; Tue, 15 Oct 2019 07:45:17 -0700 (PDT) Received: from dahern-DO-MB.local (207.190.24.244.psav-cs.smartcity.net. [207.190.24.244]) by smtp.googlemail.com with ESMTPSA id d28sm9833740vsl.5.2019.10.15.07.45.15 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 15 Oct 2019 07:45:15 -0700 (PDT) Subject: Re: Race condition in route lookup To: Martin Lau , Wei Wang Cc: Ido Schimmel , Jesse Hathaway , Linux Kernel Network Developers References: <20191010083102.GA1336@splinter> <20191011154224.GA23486@splinter> <20191012065608.igcba7tcjr4wkfsf@kafai-mbp.dhcp.thefacebook.com> <20191014172640.hezqrjpu43oggqjt@kafai-mbp.dhcp.thefacebook.com> From: David Ahern Message-ID: <9d4dd279-b20a-e333-2dd6-fe2901e67bce@gmail.com> Date: Tue, 15 Oct 2019 10:45:14 -0400 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191014172640.hezqrjpu43oggqjt@kafai-mbp.dhcp.thefacebook.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 10/14/19 1:26 PM, Martin Lau wrote: > > AFAICT, even for the route that are affected by fib6_update_sernum_upto_root(), > I don't see the RTF_PCPU route is re-created. v6 sk does > dst_check() => re-lookup the fib6 => > found the same RTF_PCPU (but does not re-create it) => > update the sk with new cookie in ip6_dst_store() > That's fine. The pcpu cache is per nexthop (fib6_nh) for a specific gateway/device. The invalidate forces another lookup for the intended destination after the change to the fib. If the lookup resolves to the same fib entry and nexthop, then re-using the same cached dst/rt6_info is ok.